Reply To: 2016 Sierra 8-Spd Issue

I bought it brand new Dec 2015 (2015 High Country 4×4, 6.2ltr V-8) with the new eight-speed Hydra-Matic 8L90 transmission. So I’ve had it a year now and have put 19k + miles it. I noticed about a month ago when the engine was cold and I went from park to drive it felt as if I was parked on a hill and the trans was in a bind, taken 1-2 seconds before roughly engaging in gear. Then it started doing it more often even when the transmission fluid temp was above 130. Well last week it began to shudder almost like driving over road strips before a stop sign. I also noticed that if I had it on cruise control between 40-60mph the tachometer would rev up every time it shuttered/vibrated. It took it back to the dealership as it is still under warranty and had the mechanic ride with me so he could see for himself what my Chevrolet was doing. He knew immediately as to what he thought was causing the vibration…torque converter he says! So as of right now it is in the shop to replace the torque converter with an upgraded one per this bulletin 15389 which provides a service procedure to reprogram the transmission control module (TCM) on certain 2015 model year Cadillac Escalade, Escalade ESV, Chevrolet Silverado, GMC Sierra, Yukon Denali and Yukon Denali XL vehicles equipped with an 8L90 8-Speed (M5U) transmission and 6.2L (L86) engine. These vehicles may have a condition in which transmission calibration allows a higher than target energy input to the torque converter clutch (TCC) under certain conditions. This may lead to faster than expected torque converter clutch material wear, and a shudder feeling.